When Shadrach, Meshach and Abed-nego were thrown into the fiery furnace, the scripture indicates that they were joined by a fourth image who was “like the Son of God.” (vs.25) Later in verse 28 the king says that it is an angel of the Lord. In the introduction to the chapter that I believe was added by Bruce R. McConkie, it reads the “Son of God preserves them.” Was it the Savior or was it an angel?
“The angel of the Lord” is an expression that is often used in the scriptures to denote the Lord, Himself. In Luke 2:9, for instance,
And, lo, the angel of the Lord came upon them, and the glory of the Lord shone round about them: and they were sore afraid.
The glory of the Lord denotes the presence of the Lord, who is called the angel of the Lord.
In another instance, when Moses ascended Mt. Horeb where he received the Ten Commandments from the Lord,
the angel of the LORD appeared unto him in a flame of fire out of the midst of a bush (Exo 3:2).
In verse 4, it is not the angel of the LORD, but the LORD himself that is referenced–
And when the LORD saw that he turned aside to see, God called unto him out of the midst of the bush, and said, Moses, Moses. (Moses 3:4)
The Joseph Smith Translation of Exodus 3:2 uses the expression the presence of the LORD, rather than the angel of the LORD.
There are also in the scriptures where the expression an angel of the LORD angel of the LORD is used, also referring to Jehovah, as in Acts 7:30—
And when forty years were expired, there appeared to him in the wilderness of mount Sina an angel of the Lord in a flame of fire in a bush.
and Judges 2:1—
And an angel of the LORD came up from Gilgal to Bochim, and said, I made you to go up out of Egypt, and have brought you unto the land which I sware unto your fathers; and I said, I will never break my covenant with you.
Here the angel of the LORD obviously refers to the LORD because the covenants of Israel are obviously made with the LORD and not with an angel.
Other references are not so definitive; and so from the scriptural citation it may not be so easily determined that reference is made to the LORD Himself rather than one of his angels.